The present invention is directed toward improving the performance of towable land leveling scrapers, known as "dirt buckets" or "scrapers" , by stabilizing the dirt bucket so as to prevent "bounce," "waddle," or "duck walking" thereby increasing operational speed and preventing wear and tear on the dirt bucket.
The dirt bucket is a device used for dirt removal and ground leveling to prepare a parcel of land for construction or agricultural purposes, although it may also be used for excavating wide trenches and sumps. During the process of ground leveling, a cutting blade located at the bottom of the dirt bucket scrapes dirt from the ground surface which is collected in the bucket portion of the device. The elevation of the cutting blade with respect to the ground surface is adjusted by the operator by raising or lowering the wheels located at the rear of the dirt bucket. Dirt buckets are frequently run in tandem, where a second dirt bucket is towed directly behind first dirt bucket, which in turn is towed by a towing vehicle. Many dirt buckets implement laser surveying systems to achieve precise leveling of the ground surface.
While performing land leveling operations and during transportation dirt buckets have been known to bounce, undulate from side-to-side, waddle and duck walk. These undesirable motions are particularly severe as the dirt bucket travels at higher speeds, causing the cutting blade to dig unevenly into the ground surface, and requiring additional leveling work to obtain a satisfactory ground surface. These undesirable motions also cause wear and tear on the components of the dirt bucket because of additional vibration and cyclical loading. When these motions occur, a dirt bucket operator must slow the machine substantially to achieve the precise leveling of the ground surface which is achievable through the use of a laser surveying system and to prevent wear and tear on the dirt bucket otherwise caused by these undesirable motions.
Different solutions have been proposed to prevent or minimize undesirable motions in dirt buckets. U.S. Pat. No. 4,389,800 discloses a land leveling scraper which includes a skid shoe system where the bottom surface of the skid shoes accommodate and follow irregularities in the ground surface being leveled, and the skid shoes are urged against the ground surface with a force proportional to the load on the bucket of the scraper. Ideally, the skid shoes automatically adjust to irregularities on the ground surface and maintain maximum contact with the ground surface because the load on the skid shoes increases as the load on the bucket increases. However, the skid shoe system disclosed in U.S. Pat. No. 4,389,800 is an integral part of the land leveling scraper as opposed to an easily installed after-market addition. Moreover, this system operates on the same hydraulics which lower and raise the bucket and thus is not independently adjustable by the operator to allow custom settings for different earth removal applications, such as digging a sump as opposed to obtaining precise leveling of the ground surface. Finally, because this system is connected to other dirt bucket hydraulics, it can be difficult to maintain.
Another attempted solution is to add additional axles and wheels to the back of the dirt bucket. However, this solution is expensive, requires additional maintenance, and prevents running dirt buckets in tandem because the additional axles and wheels on the front dirt bucket interfere with installing the towing mechanism required for connecting the rear dirt bucket.
U.S. Pat. No. 5,307,570 discloses the attachment of skid shoes to dirt buckets by spring-loaded legs. However, adjustment of the load-bearing capacity of the skid shoes requires changing of the coil compression spring. Even if the proper spring is available, the spring-loaded legs must be dismantled for installation of different springs.
For the foregoing reasons, there is a need for a stabilizing system for dirt buckets which may be readily installed to existing dirt buckets, which operates independently of the dirt bucket hydraulic system, allows tandem operation of dirt buckets, and allows for easy operator adjustment of the resisting force.